Grooveshark became a rare victim of Android Market policy on Tuesday, when Google removed the streaming music app without explanation of which policies were violated.

Unlike other streaming music services, such as Rdio and MOG, Grooveshark doesn’t license the entirety of its library. Songs are uploaded by other users, allowing Grooveshark to undercut the competiton with free web streaming and a $3 per month mobile app. Although Grooveshark has made an arrangement with EMI, a lawsuit against Universal Music Group is underway, and I wouldn’t be surprised if record labels complained. Apple yanked Grooveshark’s iPhone app last July.

But as CNet’s Greg Sandoval points out, the timing of the Android app’s removal is coincidental. Google’s general counsel, Kent Walker, is testifying on Wednesday before the House Judiciary committee, which is investigating websites that profit from piracy. Google is fending off allegations that it makes money from AdSense ads on piracy websites, and will defend its reputation by pointing to its own anti-piracy efforts.

Just one other observation: Grooveshark’s Chrome web app remains untouched, at least at the time of this writing. Granted, the Chrome Web store is much lower-profile than Android, but I’ll be interested to see whether Google starts policing this ecosystem for copyright violations as well, even if its just a collection of glorified bookmarks.